Agilent Technologies 4284A Service Manual page 69

Each board is described below.
A7 Digital Control (CPU)
The A7 Digital Control (CPU) contains the main CPU (16-bit micro processor), programmed
ROMs, RAMs, EEPROMs, and the local clock generator. This A7 board is the master con-
troller for the HP 4284A.
A9 Keyboard
The A9 keyboard is the front panel keyboard. L E D indicators, beeper, and the CONTRAST
adjustment resistor are on the A9 board.
A10 Memory Card Interface
The A10 memory card interface board is the memory card socket board.
A20 HP-16 Interface
The A20 HP-IB interface board controls the handshake between the micropocessor and
external HP-IB controller.
A30/A31 Handler Interface (Option 201/202)
The A30/A31 handler interface board interfaces between the HP 4284A and the external
handler.
A40 Scanner Interface (Option 301)
The A40 scanner interface board interfaces between the HP 4284A and the external scanner.
The A40 board has two EEPROMs for storing 128 sets of OPEN/SHORT/LOAD correction
data at each three frequencies.
A50 Bias Current Interface (Option 002)
The A50 bias current interface board is used to control the HP 42841A.
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